PW8205.TXT

PIE CHART (1K ZX-81)
By Simon Lane
from Popular Computing Weekly Vol. 1 No. 6 (27 May 1982), page 18

This program will draw a pie chart from any data you care to give it. First ask
for a title. This must be a maximum of 20 characters, and will appear above the
pie chart in the final display.

Next ask for the number of categories which must be a maximum of seven. Now ask
for the units. This is the name of whatever units each category is measured in,
for example people or days, and can have up to six characters.

Finally you are asked for the name and number in each category. The name may
contain up to nine characters. The screen is then cleared and the pie chart is
drawn. Note that the figures in the % column will not always add up to 100, due
to rounding.




Issue #5, 20.May.82, page 19

Z-CODE (00ZX81)
The following program produces coded messages that are extraordinarily
difficult to crack. For example, try and crack this message:

		"5 = AKY - 3R2Y5)KL"

    The only way to decode the above message is by using the following
program and knowing the keyword. Every message can be uniquely coded, and
another advantage is that all spaces are coded and, like letters, will appear
differently coded. Therefore, it is no good trying to count up the most used
letter or graphic symbol and calling that E or whatever - it won't work.

    The program work by taking your code word - say for example "Enigma" -
and adding it to your message text, deducting 63 where the addition yields a
final total of more than 63. The keyword is recycled every time. For example:

		ENIGMA ENIGMA ENIGMA
		NOW IS  THE T IME

    Therefore the spaces have G,E,M added to them, and the two Es, for
example, will appear differently. One will have G added and the other I.

    Enter the program as listed except for line 8070; enter *all* of it in
normal video. Save it on tape by typing as a direct command "RUN 8070". The
program will then automatically run on subsequent loadings. All you have to
do is enter your keyword when prompted, then your message.

    The message can already be in code or in a decoded state, just answer
line 150 relevant to the state of your text. By choosing a particular keyword
that your fellow spy will know, you can then publish your message. No one
will be able to decode it unless they happen to know the particular keyword.